// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/renderer/gpu/frame_swap_message_queue.h"

#include <algorithm>
#include <limits>
#include <memory>
#include <utility>

#include "base/containers/hash_tables.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "base/stl_util.h"
#include "ipc/ipc_message.h"

using std::vector;

namespace content {

class FrameSwapMessageSubQueue {
public:
    FrameSwapMessageSubQueue() { }
    virtual ~FrameSwapMessageSubQueue() { }
    virtual bool Empty() const = 0;
    virtual void QueueMessage(int source_frame_number,
        std::unique_ptr<IPC::Message> msg,
        bool* is_first)
        = 0;
    virtual void DrainMessages(
        int source_frame_number,
        std::vector<std::unique_ptr<IPC::Message>>* messages)
        = 0;

private:
    DISALLOW_COPY_AND_ASSIGN(FrameSwapMessageSubQueue);
};

namespace {

    // Queue specific to MESSAGE_DELIVERY_POLICY_WITH_VISUAL_STATE.
    class SendMessageScopeImpl : public FrameSwapMessageQueue::SendMessageScope {
    public:
        SendMessageScopeImpl(base::Lock* lock)
            : auto_lock_(*lock)
        {
        }
        ~SendMessageScopeImpl() override { }

    private:
        base::AutoLock auto_lock_;
    };

    class VisualStateQueue : public FrameSwapMessageSubQueue {
    public:
        VisualStateQueue() = default;

        ~VisualStateQueue() override = default;

        bool Empty() const override { return queue_.empty(); }

        void QueueMessage(int source_frame_number,
            std::unique_ptr<IPC::Message> msg,
            bool* is_first) override
        {
            if (is_first)
                *is_first = (queue_.count(source_frame_number) == 0);

            queue_[source_frame_number].push_back(std::move(msg));
        }

        void DrainMessages(
            int source_frame_number,
            std::vector<std::unique_ptr<IPC::Message>>* messages) override
        {
            auto end = queue_.upper_bound(source_frame_number);
            for (auto i = queue_.begin(); i != end; i++) {
                DCHECK(i->first <= source_frame_number);
                std::move(i->second.begin(), i->second.end(),
                    std::back_inserter(*messages));
            }
            queue_.erase(queue_.begin(), end);
        }

    private:
        std::map<int, std::vector<std::unique_ptr<IPC::Message>>> queue_;

        DISALLOW_COPY_AND_ASSIGN(VisualStateQueue);
    };

    // Queue specific to MESSAGE_DELIVERY_POLICY_WITH_NEXT_SWAP.
    class SwapQueue : public FrameSwapMessageSubQueue {
    public:
        SwapQueue() { }
        bool Empty() const override { return queue_.empty(); }

        void QueueMessage(int source_frame_number,
            std::unique_ptr<IPC::Message> msg,
            bool* is_first) override
        {
            if (is_first)
                *is_first = Empty();
            queue_.push_back(std::move(msg));
        }

        void DrainMessages(
            int source_frame_number,
            std::vector<std::unique_ptr<IPC::Message>>* messages) override
        {
            std::move(queue_.begin(), queue_.end(), std::back_inserter(*messages));
            queue_.clear();
        }

    private:
        std::vector<std::unique_ptr<IPC::Message>> queue_;

        DISALLOW_COPY_AND_ASSIGN(SwapQueue);
    };

} // namespace

FrameSwapMessageQueue::FrameSwapMessageQueue()
    : visual_state_queue_(new VisualStateQueue())
    , swap_queue_(new SwapQueue())
{
}

FrameSwapMessageQueue::~FrameSwapMessageQueue()
{
}

bool FrameSwapMessageQueue::Empty() const
{
    base::AutoLock lock(lock_);
    return next_drain_messages_.empty() && visual_state_queue_->Empty() && swap_queue_->Empty();
}

FrameSwapMessageSubQueue* FrameSwapMessageQueue::GetSubQueue(
    MessageDeliveryPolicy policy)
{
    switch (policy) {
    case MESSAGE_DELIVERY_POLICY_WITH_NEXT_SWAP:
        return swap_queue_.get();
        break;
    case MESSAGE_DELIVERY_POLICY_WITH_VISUAL_STATE:
        return visual_state_queue_.get();
        break;
    }
    NOTREACHED();
    return NULL;
}

void FrameSwapMessageQueue::QueueMessageForFrame(
    MessageDeliveryPolicy policy,
    int source_frame_number,
    std::unique_ptr<IPC::Message> msg,
    bool* is_first)
{
    base::AutoLock lock(lock_);
    GetSubQueue(policy)
        ->QueueMessage(source_frame_number, std::move(msg), is_first);
}

void FrameSwapMessageQueue::DidActivate(int source_frame_number)
{
    base::AutoLock lock(lock_);
    visual_state_queue_->DrainMessages(source_frame_number,
        &next_drain_messages_);
}

void FrameSwapMessageQueue::DidSwap(int source_frame_number)
{
    base::AutoLock lock(lock_);
    swap_queue_->DrainMessages(0, &next_drain_messages_);
}

void FrameSwapMessageQueue::DidNotSwap(
    int source_frame_number,
    cc::SwapPromise::DidNotSwapReason reason,
    std::vector<std::unique_ptr<IPC::Message>>* messages)
{
    base::AutoLock lock(lock_);
    switch (reason) {
    case cc::SwapPromise::SWAP_FAILS:
    case cc::SwapPromise::COMMIT_NO_UPDATE:
        DrainMessages(messages);
        swap_queue_->DrainMessages(source_frame_number, messages);
        visual_state_queue_->DrainMessages(source_frame_number, messages);
        break;
    case cc::SwapPromise::COMMIT_FAILS:
    case cc::SwapPromise::ACTIVATION_FAILS:
        // Do not queue any responses here. If ACTIVATION_FAILS or
        // COMMIT_FAILS the renderer is shutting down, which will result
        // in the RenderFrameHostImpl destructor firing the remaining
        // response callbacks itself.
        break;
    }
}

void FrameSwapMessageQueue::DrainMessages(
    std::vector<std::unique_ptr<IPC::Message>>* messages)
{
    lock_.AssertAcquired();
    std::move(next_drain_messages_.begin(), next_drain_messages_.end(),
        std::back_inserter(*messages));
    next_drain_messages_.clear();
}

std::unique_ptr<FrameSwapMessageQueue::SendMessageScope>
FrameSwapMessageQueue::AcquireSendMessageScope()
{
    return base::MakeUnique<SendMessageScopeImpl>(&lock_);
}

// static
void FrameSwapMessageQueue::TransferMessages(
    std::vector<std::unique_ptr<IPC::Message>>* source,
    vector<IPC::Message>* dest)
{
    for (const auto& msg : *source) {
        dest->push_back(*msg.get());
    }
    source->clear();
}

} // namespace content
